1 /* 2 * drivers/hwmon/nsa320-hwmon.c 3 * 4 * ZyXEL NSA320 Media Servers 5 * hardware monitoring 6 * 7 * Copyright (C) 2016 Adam Baker <linux@baker-net.org.uk> 8 * based on a board file driver 9 * Copyright (C) 2012 Peter Schildmann <linux@schildmann.info> 10 * 11 * This program is free software; you can redistribute it and/or modify it 12 * under the terms of the GNU General Public License v2 as published by the 13 * Free Software Foundation. 14 * 15 * This program is distributed in the hope that it will be useful, but WITHOUT 16 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 17 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for 18 * more details. 19 */ 20 21 #include <linux/bitops.h> 22 #include <linux/delay.h> 23 #include <linux/err.h> 24 #include <linux/gpio/consumer.h> 25 #include <linux/hwmon.h> 26 #include <linux/hwmon-sysfs.h> 27 #include <linux/jiffies.h> 28 #include <linux/module.h> 29 #include <linux/mutex.h> 30 #include <linux/of.h> 31 #include <linux/of_device.h> 32 #include <linux/of_platform.h> 33 #include <linux/platform_device.h> 34 35 /* Tests for error return values rely upon this value being < 0x80 */ 36 #define MAGIC_NUMBER 0x55 37 38 /* 39 * The Zyxel hwmon MCU is a Holtek HT46R065 that is factory programmed 40 * to perform temperature and fan speed monitoring. It is read by taking 41 * the active pin low. The 32 bit output word is then clocked onto the 42 * data line. The MSB of the data word is a magic nuber to indicate it 43 * has been read correctly, the next byte is the fan speed (in hundreds 44 * of RPM) and the last two bytes are the temperature (in tenths of a 45 * degree) 46 */ 47 48 struct nsa320_hwmon { 49 struct mutex update_lock; /* lock GPIO operations */ 50 unsigned long last_updated; /* jiffies */ 51 unsigned long mcu_data; 52 struct gpio_desc *act; 53 struct gpio_desc *clk; 54 struct gpio_desc *data; 55 }; 56 57 enum nsa320_inputs { 58 NSA320_TEMP = 0, 59 NSA320_FAN = 1, 60 }; 61 62 static const char * const nsa320_input_names[] = { 63 [NSA320_TEMP] = "System Temperature", 64 [NSA320_FAN] = "Chassis Fan", 65 }; 66 67 /* 68 * Although this protocol looks similar to SPI the long delay 69 * between the active (aka chip select) signal and the shorter 70 * delay between clock pulses are needed for reliable operation. 71 * The delays provided are taken from the manufacturer kernel, 72 * testing suggest they probably incorporate a reasonable safety 73 * margin. (The single device tested became unreliable if the 74 * delay was reduced to 1/10th of this value.) 75 */ 76 static s32 nsa320_hwmon_update(struct device *dev) 77 { 78 u32 mcu_data; 79 u32 mask; 80 struct nsa320_hwmon *hwmon = dev_get_drvdata(dev); 81 82 mutex_lock(&hwmon->update_lock); 83 84 mcu_data = hwmon->mcu_data; 85 86 if (time_after(jiffies, hwmon->last_updated + HZ) || mcu_data == 0) { 87 gpiod_set_value(hwmon->act, 1); 88 msleep(100); 89 90 mcu_data = 0; 91 for (mask = BIT(31); mask; mask >>= 1) { 92 gpiod_set_value(hwmon->clk, 0); 93 usleep_range(100, 200); 94 gpiod_set_value(hwmon->clk, 1); 95 usleep_range(100, 200); 96 if (gpiod_get_value(hwmon->data)) 97 mcu_data |= mask; 98 } 99 100 gpiod_set_value(hwmon->act, 0); 101 dev_dbg(dev, "Read raw MCU data %08x\n", mcu_data); 102 103 if ((mcu_data >> 24) != MAGIC_NUMBER) { 104 dev_dbg(dev, "Read invalid MCU data %08x\n", mcu_data); 105 mcu_data = -EIO; 106 } else { 107 hwmon->mcu_data = mcu_data; 108 hwmon->last_updated = jiffies; 109 } 110 } 111 112 mutex_unlock(&hwmon->update_lock); 113 114 return mcu_data; 115 } 116 117 static ssize_t show_label(struct device *dev, 118 struct device_attribute *attr, char *buf) 119 { 120 int channel = to_sensor_dev_attr(attr)->index; 121 122 return sprintf(buf, "%s\n", nsa320_input_names[channel]); 123 } 124 125 static ssize_t temp1_input_show(struct device *dev, 126 struct device_attribute *attr, char *buf) 127 { 128 s32 mcu_data = nsa320_hwmon_update(dev); 129 130 if (mcu_data < 0) 131 return mcu_data; 132 133 return sprintf(buf, "%d\n", (mcu_data & 0xffff) * 100); 134 } 135 136 static ssize_t fan1_input_show(struct device *dev, 137 struct device_attribute *attr, char *buf) 138 { 139 s32 mcu_data = nsa320_hwmon_update(dev); 140 141 if (mcu_data < 0) 142 return mcu_data; 143 144 return sprintf(buf, "%d\n", ((mcu_data & 0xff0000) >> 16) * 100); 145 } 146 147 static SENSOR_DEVICE_ATTR(temp1_label, S_IRUGO, show_label, NULL, NSA320_TEMP); 148 static DEVICE_ATTR_RO(temp1_input); 149 static SENSOR_DEVICE_ATTR(fan1_label, S_IRUGO, show_label, NULL, NSA320_FAN); 150 static DEVICE_ATTR_RO(fan1_input); 151 152 static struct attribute *nsa320_attrs[] = { 153 &sensor_dev_attr_temp1_label.dev_attr.attr, 154 &dev_attr_temp1_input.attr, 155 &sensor_dev_attr_fan1_label.dev_attr.attr, 156 &dev_attr_fan1_input.attr, 157 NULL 158 }; 159 160 ATTRIBUTE_GROUPS(nsa320); 161 162 static const struct of_device_id of_nsa320_hwmon_match[] = { 163 { .compatible = "zyxel,nsa320-mcu", }, 164 { }, 165 }; 166 167 static int nsa320_hwmon_probe(struct platform_device *pdev) 168 { 169 struct nsa320_hwmon *hwmon; 170 struct device *classdev; 171 172 hwmon = devm_kzalloc(&pdev->dev, sizeof(*hwmon), GFP_KERNEL); 173 if (!hwmon) 174 return -ENOMEM; 175 176 /* Look up the GPIO pins to use */ 177 hwmon->act = devm_gpiod_get(&pdev->dev, "act", GPIOD_OUT_LOW); 178 if (IS_ERR(hwmon->act)) 179 return PTR_ERR(hwmon->act); 180 181 hwmon->clk = devm_gpiod_get(&pdev->dev, "clk", GPIOD_OUT_HIGH); 182 if (IS_ERR(hwmon->clk)) 183 return PTR_ERR(hwmon->clk); 184 185 hwmon->data = devm_gpiod_get(&pdev->dev, "data", GPIOD_IN); 186 if (IS_ERR(hwmon->data)) 187 return PTR_ERR(hwmon->data); 188 189 mutex_init(&hwmon->update_lock); 190 191 classdev = devm_hwmon_device_register_with_groups(&pdev->dev, 192 "nsa320", hwmon, nsa320_groups); 193 194 return PTR_ERR_OR_ZERO(classdev); 195 196 } 197 198 /* All allocations use devres so remove() is not needed. */ 199 200 static struct platform_driver nsa320_hwmon_driver = { 201 .probe = nsa320_hwmon_probe, 202 .driver = { 203 .name = "nsa320-hwmon", 204 .of_match_table = of_match_ptr(of_nsa320_hwmon_match), 205 }, 206 }; 207 208 module_platform_driver(nsa320_hwmon_driver); 209 210 MODULE_DEVICE_TABLE(of, of_nsa320_hwmon_match); 211 MODULE_AUTHOR("Peter Schildmann <linux@schildmann.info>"); 212 MODULE_AUTHOR("Adam Baker <linux@baker-net.org.uk>"); 213 MODULE_DESCRIPTION("NSA320 Hardware Monitoring"); 214 MODULE_LICENSE("GPL v2"); 215 MODULE_ALIAS("platform:nsa320-hwmon"); 216